Dispersion and oviposition of Aedes albopictus in a Brazilian slum: Initial evidence of Asian tiger mosquito domiciliation in urban environments.

Aedes albopictus, originally considered as a secondary vector for arbovirus transmission, especially in areas where this species co-exist with Aedes aegypti, has been described in most regions of the world. Dispersion and domiciliation of Ae. albopictus in a complex of densely urbanized slums in Rio de Janeiro, Southeastern Brazil, was evidenced. In this study, we tested the hypotheses that 1) Ae. albopictus distribution in urban slums is negatively related to distance from vegetation, and 2) these vectors have taken on a domestic life style with a portion of the population feeding, ovipositing, and resting indoors. To do this, we developed an integrated surveillance proposal, aiming to detect the presence and abundance of Aedes mosquitoes. The study, based on a febrile syndrome surveillance system in a cohort of infants living in the slum complex, was performed on a weekly basis between February 2014 and April 2017. A total of 8,418 adult mosquitoes (3,052 Ae. aegypti, 44 Ae. albopictus, 16 Ae. scapularis, 4 Ae. fluviatilis and 5,302 Culex quinquefasciatus) were collected by direct aspiration and 46,047 Aedes spp. eggs were collected by oviposition traps. The Asian tiger mosquito, Ae. albopictus, was aspirated in its adult form (n = 44), and immature forms of this species (n = 12) were identified from the eggs collected by the ovitraps. In most collection sites, co-occurrence of Ae. aegypti and Ae. albopictus was observed. Key-sites, such as junkyards, thrift stores, factories, tire repair shops and garages, had the higher abundance of Ae. albopictus, followed by schools and households. We collected Ae. albopictus at up to 400 meters to the nearest vegetation cover. The log transformed (n+1) number of females Ae. albopictus captured at each collection point was inversely related to the distance to the nearest vegetation border. These results show that Ae. albopictus, a competent vector for important arboviruses and more commonly found in areas with higher vegetation coverage, is present and spread in neglected and densely urbanized areas, being collected at a long distance from the typical encounter areas for this species. Besides, as Ae. albopictus can easily move between sylvatic and urban environment, the entomological monitoring of Ae. albopictus should be an integral part of mosquito surveillance and control. Finally, key-sites, characterized by high human influx and presence of potential Aedes breeding sites, should be included in entomological monitoring.

Distribution of Haemagogus and Sabethes Species in Relation to Forest Cover and Climatic Factors in the Chapada Dos Guimarães National Park, State of Mato Grosso, Brazil.

Members of the genera Haemagogus and Sabethes are the most important biological vectors of the wild yellow fever virus (WYF) in the forested areas of the Americas. The ecologies of Haemagogus janthinomys, Hg. leucocelaenus, Sabethes chloropterus, and Sa. glaucodaemon were studied in a forest of the Chapada dos Guimarães National Park, state of Mato Grosso, Brazil, to evaluate the influence of climatic factors (temperature and relative humidity [RH]) on their abundance. We also examined the association of climate with landscape structure on species distribution patterns throughout the seasons of the year. Multiple stepwise regressions showed that RH was most likely to influence the density of mosquito populations. A multidimensional scaling (MDS) was used to evaluate the effects of forest cover on the composition of mosquito populations at different radii (100-, 250-, and 1,000-m-radius buffer areas). The MDS provided 2 dimensions with values that indicated a higher similarity in the composition of culicid populations between sites 1 and 3, while site 2 was separate from the others in the ordination space. Site 2 had a much higher forest cover ratio at 100-m radius compared with sites 1 and 3. We found a possible relationship between the forest cover and the composition of the mosquito populations only in the 100-m radius. These results enabled us to infer that RH directly favored the activity of mosquito populations and that the forest cover located closest to the sampling site may influence the species composition. Since mosquito abundance was higher in the sites with lower local forest cover, forest fragmentation may be a key factor on the presence of WYF vector.

Early Evidence for Zika Virus Circulation among Aedes aegypti Mosquitoes, Rio de Janeiro, Brazil.

During 2014-2016, we conducted mosquito-based Zika virus surveillance in Rio de Janeiro, Brazil. Results suggest that Zika virus was probably introduced into the area during May-November 2013 via multiple in-country sources. Furthermore, our results strengthen the hypothesis that Zika virus in the Americas originated in Brazil during October 2012-May 2013.

A comparative study of the effect of multiple immersions on Aedini (Diptera: Culicidae) mosquito eggs with emphasis on sylvan vectors of yellow fever virus.

The effect of multiple immersions on Haemagogus janthinomys , Haemagogus leucocelaenus , Aedes albopictus and Ochlerotatus terrens eggs was studied. Eggs were collected in April, June, October and December of 2011 in Minas Gerais, Brazil. Most of the Aedes and Ochlerotatus eggs hatched upon the first immersion, while Haemagogus eggs showed a varied instalment hatching response. The number of immersions required for hatching increased for eggs collected closer to the dry winter season.

Flight height preference for oviposition of mosquito (Diptera: Culicidae) vectors of sylvatic yellow fever virus near the hydroelectric reservoir of Simplício, Minas Gerais, Brazil.

In this study, the oviposition behavior of mosquito species exhibiting acrodendrophilic habits was investigated. The study was conducted near the Simplicio Hydroelectic Reservoir (SHR) located on the border of the states of Minas Gerais and Rio de Janeiro, Brazil. Samples were collected using oviposition traps installed in forest vegetation cover between 1.70 and 4.30 m above ground level during the months of April, June, August, October, and December of 2011. Haemagogus janthinomys (Dyar), Haemagogus leucocelaenus (Dyar and Shannon), Aedes albopictus (Skuse), and Aedes terrens (Walker) specimens were present among the collected samples, the first two of which being proven vectors of sylvatic yellow fever (SYF) in Brazil and the latter is a vector of dengue in mainland Asia. As the data set was zero-inflated, a specific Poisson-based model was used for the statistical analysis. When all four species were considered in the model, only heights used for egg laying and months of sampling were explaining the distribution. However, grouping the species under the genera Haemagogus Williston and Aedes Meigen showed a significant preference for higher traps of the former. Considering the local working population of SHR is very large, fluctuating, and potentially exposed to SYF, and that this virus occurs in almost all Brazilian states, monitoring of Culicidae in Brazil is essential for assessing the risk of transmission of this arbovirus.

Immature mosquitoes (Diptera: Culicidae) in a eutrophic landfill tank from State of Rio de Janeiro, Brazil.

INTRODUCTION: To determine the faunal composition of immature culicids inhabiting a percolation tank in the landfill of Sapucaia, State of Rio de Janeiro, Brazil, immature mosquitoes were collected over a two-day period during the third weeks of April, August and October 2011. RESULTS: The species found were Culex usquatus, Lutzia bigoti, Anopheles argyritarsis and Limatus durhamii. This study is the first to report the colonization of eutrophic breeding sites by these species. CONCLUSIONS: The oviposition behavior observed in this study suggests a secondary adaptation or change in habit to select eutrophic environments during the developmental stages of the observed species.

Feeding patterns of Culex quinquefasciatus (Diptera: Culicidae) from eastern Santa Catarina state, Brazil.

Blood-feeding sources of Culex quinquefasciatus Say (Diptera: Culicidae) collected in the eastern region of the Brazilian state of Santa Catarina were analyzed by precipitin technique. One hundred fifty-four female mosquitoes collected by CDC traps in the Navegantes municipality 13-15 February 2005 reacted to one or more of eight antisera, including chicken, dog, goat, sheep, horse, opossum, human and rodent antisera. One hundred thirty-seven specimens (89%) reacted to only one source, and 17 (11%) specimens reacted to two sources. Among the 137 specimens reacting to only one source, reactions to rodent (50.4%), sheep (5.8%), chicken (5.1%), goat (5.1%), dog (2.2%), horse (3.6%), and human (3.6%) antisera were observed. The analyzed species demonstrated a high degree of opportunistic feeding behavior in relation to host preference. Results are compared with results from similar studies, and the low proportion of reactions to human antisera is discussed.

Evaluation of mosquito (Diptera: Culicidae) species richness using two sampling methods in the hydroelectric reservoir of Simplício, Minas Gerais, Brazil.

We compared two types of light traps used for monitoring mosquito abundance in the hydroelectric reservoir of Simplício, Além Paraíba - Minas Gerais. Mosquitoes were captured bimonthly using automatic CDC and Shannon traps before the filling of the hydroelectric plant reservoir from December 2008 to December 2009. In total, 1474 specimens from 13 genera were captured. Among the captured specimens, several species known to be vectors of disease-causing agents for humans and/or animals were identified, including Anopheles aquasalis, Aedes albopictus, Coquillettidia venezuelensis, Haemagogus leucocelaenus, and Aedes scapularis. Sampling efficacy between the four capture sites was not found to be significantly different, irrespective of species captured or type of trap used. Poor correlation (r (x, y) = -0.0444) between the number of mosquito species and capture site was observed when not influenced by the type of trap used. Among the installation sites of the CDC and Shannon traps in the areas investigated, CDC traps fixed in livestock shelters obtained an overall higher abundance of species captured.